Wireless communication over large geographic areas is provided by cellular telephone networks. These network technologies have commonly been divided by generations, starting in the late 1970s to early 1980s with first generation (1G) analog cellular telephones that provided baseline voice communication, to modern digital cellular telephones. Global System for Mobile Communications (GSM) is an example of a widely employed 2G digital cellular network communicating in the 900 MHz/1.8 GHz bands in Europe and at 850 MHz and 1.9 GHz in the United States. This network provides voice communication and also supports the transmission of textual data via the Short Messaging Service (SMS). SMS allows a wireless communications device (WCD) to transmit and receive text messages of up to 160 characters, while providing data transfer to packet networks, Integrated Services Digital Network (ISDN) and Plain Old Telephone Service (POTS) users at 9.6 Kbps. The Multimedia Messaging Service (MMS), an enhanced messaging system allowing for the transmission of sound, graphics and video files in addition to simple text, has also become available in certain devices. Soon, emerging technologies such as Digital Video Broadcasting for Handheld Devices (DVB-H) will make streaming digital video, and other similar content, available via direct transmission to a WCD. While long-range communication networks like GSM are a well-accepted means for transmitting and receiving data, due to cost, traffic and legislative concerns, these networks may not be appropriate for all data applications.
Short-range wireless networks provide communication solutions that avoid some of the problems seen in large cellular networks. Bluetooth™ is an example of a short-range wireless technology quickly gaining acceptance in the marketplace. A 1 Mbps Bluetooth™ radio may transmit and receive data at a rate of 720 Kbps within a range of 10 meters, and may transmit up to 100 meters with additional power boosting. Enhanced Data Rate (EDR) technology, which is also available, may enable maximum asymmetric data rates of 1448 Kbps for a 2 Mbps connection and 2178 Kbps for a 3 Mbps connection. In addition to Bluetooth™, other popular short-range wireless networks include for example IEEE 802.11 Wireless LAN (WLAN) operating in the Industrial Scientific Medical frequency band at 2.4 GHz. and in the 5 GHz frequency band. Other popular short-range wireless networks include for example Wireless Universal Serial Bus (WUSB), Ultra Wideband (UWB), ZigBee (IEEE 802.15.4 and IEEE 802.15.4a). Each of these exemplary wireless mediums has features and advantages that make them appropriate for various applications. The IEEE 802.11 Standard-2007 entitled “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”, published by the IEEE Computer Society, 12 Jun. 2007, is incorporated herein by reference.
The Wireless Gigabit Alliance (WGA) is developing a new, standardized short-range, wideband wireless technology within the IEEE 802.11 Wireless LAN Standard, to transmit data, video, and other content using the unlicensed 60 GHz frequency band, to personal computers, high definition televisions, mobile media players, and the like. The WGA Draft Specification entitled “WGA-redline-D05r0”, prepared by the WGA Technical Working Group, dated Jul. 30, 2009, and publicly available thru the WGA, is incorporated herein by reference. The 60 GHz frequency band enables the transmission of large bandwidth data streams with a high quality of service (QoS). However, transmissions in the 60 GHz band tend to be directional and may be limited to line-of-sight. Thus, the Wireless Gigabit Alliance (WGA) incorporates into its new standard, a multi-band radio capability to enable a pair of wireless devices (STAs) to simultaneously operate in more than one band. A pair of wireless devices may transfer their communications session when conditions cause error rates to increase. A communications session may be transferred from using the 60 GHz frequency band to using a lower frequency band, such as the 5 GHz frequency band or the 2.4 GHz frequency band that are omnidirectional and not limited to line-of-sight, but at a sacrifice of available bandwidth. The transmitting wireless device (STA) sends a Fast Session Transfer (FST) Setup Request frame to the other multi-band capable STA, on the current operating channel, which remains pending until an FST Setup Response has been received from that STA. It is likely the QoS and the size of data packets that can be provided is not adequate at the requested frequency band and the transfer cannot be made. Transferring from one band to another during a communications session needs to be as seamless as possible to avoid perceptible interruptions in the delivery of content to the receiving device.